A. Field of the Invention
This invention relates to anchor booms, davits, and fairleads, and recovery and storage devices for anchors.
B. The Prior Art
Over-the-gunnel anchor devices fall generally into two classes: bow rollers and boom or pulpit type. The boom or pulpit type anchor device ordinarily comprises a roller or fairlead permanently mounted on a pulpit, bow sprit or boom out over the water. Such a mount provides clearance from the side and gunwale as the anchor is retrieved and stowage of sorts on the pulpit, sprit or boom. Such devices are excellent for the retrieval of anchors, but are well known to create a stall problem wherever the operation requires the shank of an anchor hanging vertically to engage and circumvent a roller at angles of about 60.degree.-90.degree.. This can occur when operation is by winch or windless as well as (usually at the lower angle range) by hand operation. In such cases the head of the shank ordinarily comes to rest against the roller and a disproportionate force is required to bring the shank over the roller.
At least three approaches to a solution to the stall problem are noted in examination of the prior art.
U.S. Pat. No. 2,899,924 to Good taught a dipping boom which was ordinarily dipped for the entire operation of dropping, riding, and in this position could easily receive the shank of the anchor from a less unobtainable position. While readily workable, this type of boom was easily broken because boats at anchor often "sail" from side to side creating enormous transverse forces; so that the axis of the boom, when left in the dipped position had to absorb these forces in a situation where the axle mounts were subjected to excessive moments of force created by high leverage. When left in the locked position, the lock was subject to shear from transverse forces as well as excessive upward force on the lock created by the downward pull of the anchor rode.
U.S. Pat. No. 3,865,060 to Dennis, et al. taught a guide arm 12 which could assume a straight or dipped position but which, like the Good device, was designed to ride at, and subject the guide to enormous transverse forces while in, the dipped position.
U.S. Pat. No. 3,635,187 to Webb describes a guide channel which slides within and tilts from a second member which which in turn slides in the boom. Such an arrangement while theoretically workable, is subject to jamming and, again, it does not solve the problem of the transverse force.
Any simple solution to the stall problem which would avoid secondary problems associated with transverse forces would represent a significant advance in the art.